Column Basics

Columns define the structure of your tables. Every column has a type and optional modifiers that control validation, defaults, and behavior.

Column Types

Astroladb provides two levels of column types:

Semantic Types - High-level types with built-in validation (recommended)
Low-Level Types - Direct SQL type mappings for custom cases

Required vs Optional

By default, all columns are required (NOT NULL). This is an opinionated design choice that encourages explicit data modeling.

Use .optional() to allow NULL values:

export default table({
  id: col.id(),
  name: col.name(), // Required - NOT NULL
  bio: col.text().optional(), // Optional - allows NULL
  website: col.url().optional(), // Optional - allows NULL
});

Why Required by Default?

Required columns prevent common bugs:

Forced to think about data completeness
Clearer data contracts
Fewer defensive null checks in application code

Make fields optional only when NULL has a clear semantic meaning (e.g., “not provided” vs. “empty string”).

Default Values

Use .default() to set a value for new rows when no value is provided.

export default table({
  id: col.id(),
  title: col.string(200),
  status: col.string(20).default("draft"),
}).timestamps();

Unique Constraints

Use .unique() to ensure no duplicate values exist in a column.

export default table({
  id: col.id(),
  email: col.email().unique(),
  username: col.string(50).unique(),
  display_name: col.string(100), // Not unique - duplicates allowed
});

Combining Modifiers

Chain modifiers together for precise column definitions.

export default table({
  id: col.id(),
  website: col.url().optional().unique(),
  nickname: col.string(30).optional().default("Anonymous"),
});